Oct 01

Weather with Python, TkInter, Raspberry Pi…

Just messing around this weekend with some Python and TkInter. I put together a little weather app which uses Weather Underground’s API to grab the current local weather conditions (or the weather conditions from the state and city specified in the script) and creates a window to display the weather using TkInter widgets.

The script is available on GitHub. You will need a Weather Underground API Key which you can get for free. The free key allows 500 free API calls per day.

The following information about the current weather conditions is displayed: observation location, observation time, weather conditions (clear, cloudy, etc), a visible representation (icon) of the current conditions, temperature in Fahrenheit, and relative humidity. Here is what my weather app looks like running on the Raspberry Pi.

Took me a bit to make the icon image to display correctly. The code snippet Display an Image from a URL (Tkinter, Python) helped me get it working.
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Sep 25

Some VCAP 6.5 DCV Design Exam Study Notes

A couple weeks ago I sat and passed the VCAP 6.5 Datacenter Design Exam. It was a good but tough exam. The VCAP 6.5 Design exam is a bit different from past VCAP Design Exams – there are no Visio type design questions (I did not take the VCAP6, but based on the blueprint it looks like it was mostly Visio). The VCAP6.5 Design exam is made up of multiple choice and “drag and drop” questions.

Couple of tips for the exam:

  • Read the Exam Prep Guide!!! Everything you need to be successful is there (except experience).
  • When taking the exam MAKE SURE YOU READ THE QUESTION or DESIGN SCENARIO completely, then read it again before selecting your answers or completing the question activity.
  • You are able to flag questions for review – but use this wisely. If you are prepared – trust your gut – don’t second guess yourself.
  • Take your time. Since there are no Visio style questions you are given plenty of time (IMHO) to complete the exam. Relax, read the question, answer, move on.
  • Technical tip: Have a deep understand of dependencies required for, and limitations of, vSphere features and services and how these dependencies may impact the ability to meet a design requirement or may introduce risks into a design.

Here are the VMware certification official exam details:

VMware Certified Advanced Professional 6.5 – Data Center Virtualization Design Exam
Certification Page: https://mylearn.vmware.com/mgrReg/plan.cfm?plan=102518&ui=www_cert
3V0-624 Exam Page: https://mylearn.vmware.com/mgrReg/plan.cfm?plan=102526&ui=www_cert
Prep-Guide: https://mylearn.vmware.com/lcms/web/portals/certification/exam_prep_guides/Exam_Prep_Guide_VCAP6.5-DCV_Design.pdf

I did not give myself very long to prepare. I focused a majority of my prep on the new features available in vSphere 6.5 and around the upgrade/migration to vSphere 6.5 and the VCSA. Here are some notes I jotted while studying with links to resources (all of which can be found in the Prep-Guide):
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Sep 24

VMware Free Self-paced eLearning

Some free elearning resources for my ITN classes (and for everyone) – here are some great free self-paced elearning for vSphere 6 and vSphere 6.5.


Really well done foundation level online courses for datacenter virtualization, desktop virtualization, network virtualization, and more…

If you are new to vSphere or looking for a good overview of the fundamentals and available features in vSphere 6.x, Horizon, or NSX these elearning courses are AWESOME (and FREE!).


Aug 14

Recreating a vmdk descriptor file with vmkfstools

A VMware virtual machine disk is made up of two files: the .vmdk file and the -flat.vmdk file. The .vmdk file is the descriptor file and the -flat.vmdk file contains the data. If you have the -flat.vmdk file you can recreate the descriptor file using vmkfstools. This VMware KB: Recreating a missing virtual machine disk descriptor file (1002511) walks through the process.

This just saved my butt (again, but it has been awhile) so putting it here for future reference.

Jul 17

Jumbo Frames – Make sure it is setup end-to-end.

Working with a customer the other day to migrate his direct connect SimpliVity deployment to a 10 GbE switch topology to facilitate adding a couple of compute nodes to expand the CPU and memory resources available to the cluster. He went through the migration but could not get things to work correctly. The issue ended up being the MTU configuration on the physical switch.

Mis-configuration of the physical switch is probably the most common issue I come across when configuring virtual networking to use Jumbo Frames. The configuration varies from switch to switch – vendor to vendor. On some switches the configuration is done globally, on other switches it is configured on individual ports, and on some switches it must be enabled globally and configured per port.

Jumbo Frames must be configured correctly end-to-end. This means on the vSwitch, vmkernel interfaces, physical switches, endpoint – everything must be configured to support the larger frames end-to-end. Using larger frames will provide more efficient processing of network traffic (in many cases) but it does require a bit more complexity. If any part of the path is mis-configured, network frames larger than 1500 may not pass. If they do pass they will be fragmented, which defeats the purpose of using Jumbo Frames.
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Jul 03

DIY Garage Workbench

This post is not about virtualization, my home lab, or technology. Going a little low tech here to share a DIY project I did over the weekend, a mobile garage workbench using some free plans I found over at Shanty2Chic.com.

The workbench turned out really nice, is very sturdy, and easy to move around. I haven’t decided to paint it or not. Will probably just leave it raw and put a coat of clear poly on the top and shelf to seal them. The lumber and screws required to build the workbench came in at $63 from Lowe’s and the casters were $24, so all total $87 (plus the cost of the Kreg R3 Jig Kit which I will definitely be able to use for other projects). Took just a few hours to put it all together. Going to modify the plans a bit to build a 4′ one out of pressure treated wood for wife to use as a potting bench.
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Jun 20

New Book – VMware vSphere 6.5 Host Resources Deep Dive

Just ordered a copy of Host Resources Deep Dive by @FrankDenneman and @NHagoort. It is on the way!!!

“The VMware vSphere 6.5 Host Resources Deep Dive is a guide to building consistent high-performing ESXi hosts. A book that people can’t put down. Written for administrators, architects, consultants, aspiring VCDX-es and people eager to learn more about the elements that control the behavior of CPU, memory, storage and network resources.”

I have really been looking forward to this one. Can’t wait to dive in 🙂

Jun 19

Using vSphere HA to Protect vCenter

Had a interesting “discussion” the other day with someone who wasis convinced that it is a best practice is to always deploy vCenter as a separate physical Windows server. One of the reasons for this, in his opinion, was that the vCenter Server could not be protected with vSphere High Availability (HA) since vCenter is required for vSphere HA to function. This is a common misunderstanding of how vSphere HA functions. vCenter is required to configure vSphere HA but once vSphere HA is configured vCenter is NOT required for vSphere HA to protect virtual machines in the cluster.

The ability to provide HA protection of the vCenter Server is one of benefit of deploying vCenter as a virtual machine. Virtualizing vCenter Server also allows you to use the vCenter Server Appliance (VCSA) which saves you a Windows license. vSphere HA can also be used to protect a vCenter Server deployed on a Windows Virtual Machine.

Here is a quick video I did in my lab environment running vSphere 6.5 (I have also tested this on 5.5 and 6.0) which demonstrates how vSphere HA will restart the PSC and vCenter Server in the event of a host failure.

I am running the VCSA in the lab with two VCSAs deployed, one as an external PSC and one a the vCenter Server. For the purpose of the demo I have vSphere DRS set to partially automated to keep VMs from moving around and I have both the VCSA running the PSC and the VCSA running the vCenter Server on the same host. The vSphere HA configuration is the default, except I have disabled admission control due to my resource constraints in the lab. When I power off the host running the VCSAs, they restart on the surviving host in my management cluster.

The little Python script I used in the demo to check if the servers were up or down can be found here: https://github.com/herseyc/PythonScripts/blob/master/upordown.py

Post any questions in the comments. Thanks!

Jun 14

It’s been a while…

It has been a good bit since I posted anything new. Just busy with work, family, and other stuff. Some new stuff coming soon. I promise.

Apr 23

Setting up the Weathervane Benchmarking Tool in the Home Lab

If you are looking for something to do in your vSphere home lab this is a neat little project: Weathervane Open Source Benchmarking Tool. Standing up Weathervane in the home lab will provide hands-on for developing skills including creating a template VM, creating a guest customization specification, working with some basic Linux commands, working with an app with multiple tiers, cloning VMs, and monitoring performance metrics.

The architecture of Weathervane can be as simple or complex as you want to make it. The tool provides a way to generate a predictable load to help you gain some experience with deploying a multi-tier application, benchmarking the application, and monitoring performance in a virtualized environment.

Weathervane includes an Auction application made up of different services: workload driver (simulates users accessing the application), web services, database services, application services, etc. All services can be run from a single VM or can be provided across several VMs. This allows for things to be configured more like a “real world” environment and to spread load across multiple guests which can be spread across multiple hosts in a cluster. Here is the logical layout of how I have Weathervane deployed in my home lab:

The Weathervane user guide, located on github, is very detailed and provides step-by-step instructions for deploying, configuring, and running Weathervane. This post provides an overview of how I set up Weathervane in my home lab, an example of the results generated from the Weathervane runs, and a look at the performance metrics I observed in lab during the Weathervane runs.
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